1. Field of the Invention
The present invention relates in general to drive devices for driving memory discs or the like, and more particularly to drive devices for driving magneto-optical discs.
2. Description of the Prior Art
Conventional magneto-optical disc drive drives comprise generally a motor-driven disc rotor to which a magneto-optical disc is detachably connected. The drive devices further comprise an optical pick-up mechanism having a moving part which is, when the disc is set in the device, located at one side of the disc. The moving part moves in a radial direction of the disc. At the other side of the disc set in the drive device, there is arranged a magnetic field modulation head which can produce a modulated magnetic field. When, the disc is rotated and the magnetic field modulation head is energized, a laser beam is applied to the disc from the moving part of the optical pick-up mechanism, data is recorded onto the disc or data is read from the disc. The data reading is achieved by detecting the laser beam reflected by the disc.
However, due to their inherent construction, the above-mentioned conventional drive devices have the following drawbacks.
First, they are bulky in construction. That is, in such conventional devices, a space must be provided for the disc loading mechanism and another space must be provided for loading the disc.
Second, the magnetic field modulation head used must have a marked power. That is, for dust protection, the disc is housed in a disc case. However, this necessitates an increased distance between the disc and the magnetic field modulation head.
Third, due to the nature of the drive devices of the type wherein a disc is detachably connected to the disc rotor, it is difficult to properly set the disc to be concentric relative to the rotation center of the disc rotor. As is known, eccentricity of the disc relative to the disc rotor causes frequent movement of the moving part of the optical pick-up mechanism, so that moving elements of the moving part tend to shorten their lives.